1. Field of the Invention
My invention relates to bird feeders, and more particularly to improved feeders from which small animals such as squirrels and raccoons successfully steal or eat food. The use of bird feeders as lawn and garden implements has become a widespread hobby for a major part of the consumer public. While most persons who maintain bird feeders intend that only birds will feed from them, it is common for squirrels and raccoons to steal much of the food from such feeders, much to the displeasure of the people who have placed the feeders with intent to attract song birds.
2. Description of the Prior Art
There have been many attempts to provide bird feeders with means for preventing squirrels, large birds and the like from gaining access to feed within a feeder. A serious deficiency of many such feeders is believed to result from an insufficient appreciation of the extreme agility and perserverence of squirrels, and similar animals.
In a number of these feeders (U.S. Pat. Nos. 5,255,631; 5,207,181; 5,195,460; 5,048,461) a base member which supports a supply of food carries a spring means which supports a secondary masking, or shield member. The masking member is sufficiently above the food supply to allow birds access to the food. Being of relative light weight (1 to 2 ounces), the birds do not compress, or activate, the spring means. Squirrels or like-sized animals, however, have sufficient weight to compress the spring means, thereby lowering the masking member to where it occludes access to the food supply. This form of feeder has the general disadvantage of allowing feeding access from only one elevation, or from one side of a rectangular box like structure, which limits the number of birds which can feed at any one time. This characteristic also limits the viewing opportunity for owners, as the feeder has to be precisely aligned to the viewer for the viewer to see the feeding area, and thus the birds.
In other prior art feeders (U.S. Pat. Nos. 5,964,183; 5,720,238; 5,375,558; 5,195,459; 5,163,382; 5,156,112; 4,646,686), a metal or wire sleeve surrounds the sides of a tower. A spring means supports the sleeve relative to the tower at a position such that openings in the sleeve ordinarily register with feed holes in the sides of the tower. If a squirrel or other animal of like weight clings to the sleeve, its weight compresses the spring means, moving the openings in the sleeve downward so they no longer register with the holes in the tower, thus preventing the squirrel from reaching food. This type of feeder depends on the registration and de-registration of pairs of holes. This form of feeder suffers from the disadvantage that it is telescopic in its movements, which means the outer sleeve moves parallel to the inner tower. This telescopic movement tends to bind, or catch, somewhat more easily than is desired. When the mechanism binds, the outer sleeve does not fully drop, or slide all the way downward, which results in the feeding ports not being totally occluded, thus allowing the squirrel an opportunity to feed. Moreover, because of the critical tolerances of the inner and outer sleeves, this binding can occur once the outer sleeve has dropped fully, and has occluded the feeding ports. When binding occurs at this position, the outer sleeve does not spring upward upon departure of the squirrel, thus rendering the feeder useless to birds that subsequently visit to partake of food.
It is highly desirable that a bird feeder which prevents squirrels from feeding not be disabled from feeding birds if it has been activated to prevent a squirrel from feeding. It is also highly desirable that a bird feeder mechanism operative to prevent squirrel feeding not be damaged if the feeder is knocked or slammed by a larger animal such as a raccoon, and another object of the present invention is to provide such an improved bird feeder.
Still other prior feeders (U.S. Pat. Nos. 4,030,451; 4,031,856; 4,102,308) utilize an over-sized dome structure, or inverted dish, to shield a food tray from squirrels; or attempt to fence squirrels out by having a wire mesh surround the food delivery means (U.S. Pat. No. 4,434,745). These feeders have the disadvantage of excluding certain types of desirable birds; and, because of their utilitarian armaments, these types of feeders are deemed aesthetically undesirable by a large segment of the public.
One general object of the invention is to provide a bird feeder which is attractive to many birds, but which does not often lose its contents to a very diligent and extremely agile squirrel. One of the primary attending objects of the present invention is to provide a bird feeder which will more effectively prevent squirrels and raccoons from feeding from the feeder. Another more specific object of the present invention is to provide a bird feeder wherein the forces which a squirrel or like animal imparts to the operative food-denying mechanism of the feeder operate in complex manners, through plural or even infinite degrees of mechanical freedom, so that a squirrel or like animal cannot learn how to defeat the mechanism and steal food from the feeder. As will be seen, the present invention utilizes a shielding mechanism that behaves in a fashion substantially like a universal-joint. It is believed that no other prior feeders employ this universal-joint type of mechanism. Other objects will be mentioned below, or will become obvious as the description proceeds.